EP1182366A1

EP1182366A1 - Screw threaded members

Info

Publication number: EP1182366A1
Application number: EP01306887A
Authority: EP
Inventors: Michael E. Ward; John H. Siegenthaler
Original assignee: Illinois Tool Works Inc
Current assignee: Illinois Tool Works Inc
Priority date: 2000-08-24
Filing date: 2001-08-14
Publication date: 2002-02-27
Also published as: US20020025240A1; US6726420B2

Abstract

A screw threaded member has larger thread clearances than usual to accommodate paint or other coatings. Typically the screw thread (10) has a pitch diameter increased by not less than 26% of the tooth height of the thread and may have an asymmetric thread configuration.

Description

The invention relates generally to screw threads, and more particularly to threads having clearance configurations.
Nuts configured for removing coating, for example paint, from threaded shafts upon installation thereabout are known generally. One known nut is the PAINTSCRAPER REPS nut by ITW Shakeproof, of Elgin, Illinois, USA, which includes a plurality of slots with a cutting edge extending generally radially from the threaded bore.
In some applications, particularly where the coating is heavy or thick, installation of the nut about the shaft is stalled by the increasing accumulation of coating between the threads. FIG. 4 illustrates a clearance area, which is normalized at 100% for comparative purposes, between internal and external screw threads manufactured in compliance with industry basic standard specifications.
An object of the invention is to provide in some embodiments thereof novel thread forms having improved clearance configurations, for example to accommodate increased amounts of coating between mated internal and external threads.
Particular embodiments in accordance with this invention will now be described with reference to the accompanying drawings; in which;-
FIG. 1 is a partial sectional view of a thread form according to a first exemplary embodiment of the invention;
FIG. 2 is a partial sectional view of a thread form according to a second exemplary embodiment of the invention;
FIG. 3 is a partial sectional view of a thread form according to another exemplary embodiment of the invention;
FIG. 4 is a partial sectional view of a thread form according to yet another exemplary embodiment of the invention;
FIG. 5 is partial sectional view of a nut comprising one or more of the thread alternative forms of the present invention in combination;
FIG. 6 is a partial top plan view of the nut of FIG. 5; and
FIG. 7 is a bottom plan view of the nut of FIG. 5.
FIG. 1 illustrates mated internal and external threads having an increased clearance therebetween that is 170% in relation to the clearance illustrated in FIG. 4, discussed above.
In one embodiment, the clearance in FIG. 1 is increased by increasing the minor diameter of the internal thread. According to this configuration, the tooth 10 in FIG. 1 is of an internal thread formed in a bore, for example in the coating clearing nut 20 having generally radially extending slots 22, illustrated in FIGS. 5-7.
The exemplary nut 20 of FIGS. 5 and 7 includes a washer 24 assembled therewith. In other embodiments, the nut does not include the slots or washer. Still more generally, the screw thread may be formed in any bore extending partially or fully through any body member, for example a plate or some other article besides a nut.
In some internal thread embodiments, the minor diameter is increased outside the industry standard basic minor diameter tolerance specified for the particular thread size. The extent to which the minor diameter is increased is limited to some extent by the loading requirements, although in some embodiments the axial length of the threaded bore may be increased to compensate for the decreased load bearing capacity of the truncated thread.
In a more particular embodiment, the internally threaded body member, or one of the exemplary nuts, has a coarse thread size of 4 mm or more, and the thread has a minor diameter not less than 7.7% more than an industry standard basic minor diameter specified for the corresponding thread size.
According to this interpretation of FIG. 1, the minor diameter is approximately the same as the pitch diameter. The pitch diameter may be an industry standard, for example the ISO industry standard, basic pitch diameter specified for a particular thread size. In other embodiments, however, the pitch diameter may be outside industry standard basic pitch diameter tolerance.
In an alternative embodiment, the clearance in FIG. 1 is increased by decreasing the major diameter of the external thread. According to this configuration, the tooth 10 in FIG. 1 is a tooth of an external thread formed on a shaft, for example a bolt.
In some external thread embodiments, the major diameter is outside the industry standard basic major diameter tolerance specified for the particular thread size. The extent to which the major diameter is decreased is limited to some extent by the loading requirements.
In a more particular embodiment, the externally threaded body member has a coarse thread size of 4 mm or more, and the thread has a major diameter not less than 7.7% less than an industry standard basic major diameter specified for the corresponding thread size.
According to this alternative interpretation of FIG. 1, the major diameter is approximately the same as the pitch diameter. The pitch diameter may be an industry standard, for example the ISO industry standard, basic pitch diameter specified for a particular thread size. In other embodiments, however, the pitch diameter may be outside industry standard basic pitch diameter tolerance.
FIG. 2 illustrates mated internal and external threads having an increased clearance therebetween that is 200% in relation to the clearance illustrated in FIG. 4.
In one embodiment, the clearance in FIG. 2 is increased by increasing the pitch diameter of the internal thread. According to this configuration, the tooth 30 in FIG. 2 is of an internal thread formed in a bore, for example of the coating clearing nut 20 of FIGS. 5-7.
In an alternative embodiment, the clearance in FIG. 2 is increased by decreasing the pitch diameter of the external thread. According to this configuration, the tooth 30 in FIG. 2 is of an external thread formed on a shaft, for example a bolt shaft.
In some external thread embodiments, the pitch diameter is outside the industry standard basic pitch diameter tolerance specified for the particular thread size.
In an exemplary internal thread embodiment, the internally threaded body member has a coarse thread size of 4 mm or more, and the thread has a pitch diameter not less than 4.5% greater than an industry standard basic pitch diameter specified for the thread size.
In an exemplary external thread embodiment, the externally threaded body member, or shaft, has a coarse thread size of 4 mm or more, and the thread has a pitch diameter not less than 4.5% less than an industry standard basic pitch diameter specified for the thread size.
In another alternative pitch diameter embodiment, applicable to both internal and external threads, the thread has a pitch diameter increased not less than 26% of a tooth height thereof.
FIG. 3 illustrates mated internal and external threads having an increased clearance therebetween by modifying both pitch diameter and the major or minor thread diameter.
In FIG. 3, the exemplary clearance is 230% in relation to the clearance illustrated in FIG. 4. The exemplary clearance percentage may be obtained in an internal thread having a pitch diameter increased not less than 18% of tooth height in combination with a minor diameter increased not less than 41% of the tooth height. The exemplary clearance percentage may also be obtained in an external thread having a pitch diameter decreased not less than 18% of tooth height in combination with a major diameter decreased not less than 41% of tooth height.
Several exemplary internal thread nut embodiments having both increased pitch and minor diameters are as follows: a 4 mm coarse thread size having 0.70 mm thread pitch, the pitch diameter is not less than 3.71 mm, the minor thread diameter is not less than 3.49 mm; a 5 mm coarse thread size having 0.8 mm thread pitch, the pitch diameter is not less than 4.69 mm, the minor thread diameter is not less than 4.46 mm; a 6 mm coarse thread size having 1.00 mm thread pitch, the pitch diameter is not less than 5.60 mm, the minor thread diameter is not less than 5.30 mm; an 8 mm coarse thread size having 1.25 mm thread pitch, the pitch diameter is not less than 7.52 mm, the minor thread diameter is not less than 7.16 mm; a 10 mm coarse thread size having 1.5 mm thread pitch, the pitch diameter is not less than 9.44 mm, the minor thread diameter is not less than 9.03 mm; a 12 mm coarse thread size having 1.75 mm thread pitch, the pitch diameter is not less than 11.36 mm, the minor thread diameter is not less than 10.89 mm; a 14 mm coarse thread size having 2.0 mm thread pitch, the pitch diameter is not less than 13.28 mm, the minor thread diameter is not less than 12.75 mm; and a 16 mm coarse thread size having 2.0 mm thread pitch, the pitch diameter is not less than 15.37 mm, the minor thread diameter is not less than 14.91 mm.
Several exemplary external threaded shaft embodiments having both decreased pitch and major diameters are as follows: a 4 mm coarse thread size having 0.70 mm thread pitch, the pitch diameter is not less than 3.71 mm, the minor thread diameter is not less than 3.49 mm; a 5 mm coarse thread size having 0.8 mm thread pitch, the pitch diameter is not less than 4.69 mm, the minor thread diameter is not less than 4.46 mm; a 6 mm coarse thread size having 1.00 mm thread pitch, the pitch diameter is not less than 5.60 mm, the minor thread diameter is not less than 5.30 mm; an 8 mm coarse thread size having 1.25 mm thread pitch, the pitch diameter is not less than 7.52 mm, the minor thread diameter is not less than 7.16 mm; a 10 mm coarse thread size having 1.5 mm thread pitch, the pitch diameter is not less than 9.44 mm, the minor thread diameter is not less than 9.03 mm; a 12 mm coarse thread size having 1.75 mm thread pitch, the pitch diameter is not less than 11.36 mm, the minor thread diameter is not less than 10.89 mm; a 14 mm coarse thread size having 2.0 mm thread pitch, the pitch diameter is not less than 13.28 mm, the minor thread diameter is not less than 12.75 mm; and a 16 mm coarse thread size having 2.0 mm thread pitch, the pitch diameter is not less than 15.37 mm, the minor thread diameter is not less than 14.91 mm.
FIG. 4 illustrates in phantom lines the thread having an asymmetric flank configuration to further increase thread clearance. More particularly, the non-load bearing flank of the screw thread is reduced in size relative to an opposite load bearing flank thereof, for example by removing a portion thereof corresponding to that delineated by the phantom lines.
The portions of the non-load bearing flank that are removed depends to some extent on the load bearing requirements and on where the coating is accumulated.

Claims

An internally threaded body member comprising:

a bore extending at least partially into the body member, the bore having a screw thread disposed therein, the screw thread having a pitch diameter increased not less than 26% of a tooth height thereof.
A coating clearance nut having a coarse thread size of 4 mm or more and a thread pitch of 0.7 or more, comprising:

the screw thread disposed in a bore of the nut,

the screw thread having a pitch diameter not less than 4.5% greater than an industry standard basic pitch diameter specified for the thread size.
An internally threaded body member comprising:

a bore extending at least partially into the body member, the bore having a screw thread disposed therein, the screw thread having a pitch diameter specified;

the screw thread having a minor diameter approximately the same as the pitch diameter.
An internally threaded body member having a coarse thread size of 4 mm or more and a thread pitch of 0.7 or more, comprising:

a bore extending at least partially into the body member, the thread disposed in the bore,

the thread having a minor diameter not less than 7.7% more than an industry standard basic minor diameter specified for the thread size.
An internally threaded body member comprising:

a bore extending at least partially into the body member, the bore having a helical screw thread disposed therein,

the screw thread has an asymmetric flank configuration.
An internally threaded body member comprising:

a bore extending at least partially into the body member, the bore having a screw thread disposed therein,

the screw thread having a pitch diameter increased not less than 18% of a tooth height thereof,

a minor diameter of the threaded bore is increased not less than 41% of the tooth height.
A member or a nut, according to any one of the preceding claims, has a 4 mm coarse thread size having 0.70 mm thread pitch, with the pitch diameter not less than 3.71 mm, and the minor thread diameter not less than 3.49 mm; or,

has a 5 mm coarse thread size having 0.8 mm thread pitch, with the pitch diameter not less than 4.69 mm, and the minor thread diameter not less than 4.46 mm; or,

has a 6 mm coarse thread size having 1.00 mm thread pitch, with the pitch diameter not less than 5.60 mm, and the minor thread diameter not less than 5.30 mm; or,

has an 8 mm coarse thread size having 1.25 mm thread pitch, with the pitch diameter not less than 7.52 mm, and the minor thread diameter not less than 7.16 mm; or,

has a 10mm coarse thread size having 1.5 mm thread pitch, with the pitch diameter not less than 9.44 mm, and the minor thread diameter not less than 9.03 mm; or,

has a 12 mm coarse thread size having 1.75 mm thread pitch, with the pitch diameter not less than 11.36 mm, and the minor thread diameter not less than 10.89 mm; or,

has a 14mm coarse thread size having 2.0mm thread pitch, with the pitch diameter not less than 13.28 mm, and the minor thread diameter not less than 12.75 mm; or,

has a 16 mm coarse thread size having 2.0 mm thread pitch, with the pitch diameter not less than 15.37 mm, and the minor thread diameter not less than 14.91 mm.
A member or a nut according to any one of the preceding claims, wherein the member is a nut having a plurality of slots extending generally radially from the threaded bore, each slot having a cutting edge.
An externally threaded body member comprising:

a shaft having a screw thread disposed thereabout,

the thread having a tooth height,

the screw thread having a pitch diameter decreased not less than 26% of a tooth height thereof.
A coating clearance bolt having a coarse thread size of 4 mm or more and a thread pitch of 0.7 or more, comprising:

the thread disposed about a shaft of the bolt,

the screw thread having a pitch diameter not less than 4.5% less than an industry standard basic pitch diameter specified for the thread size.
An externally threaded body member having a coarse thread size of 4 mm or more, comprising:

the screw thread disposed about a shaft portion;

the screw thread having a major diameter not less than 7.7% less than an industry standard basic major diameter specified for the thread.
An externally threaded body member comprising:

an external screw thread disposed about a shaft;

the screw thread having a pitch diameter;

the screw thread having a major diameter approximately the same as the pitch diameter.
A member or bolt according to any one of claims 9 to 12, has a 4 mm coarse thread size having 0.70 mm thread pitch, with the pitch diameter not more than 3.38 mm, and the major thread diameter not more than 2.99 mm; or,

has a 5 mm coarse thread size having 0.80 mm thread pitch, with the pitch diameter not more than 4.27 mm, and the major thread diameter not more than 3.81 mm; or

has a 6 mm coarse thread size having 1.00mm thread pitch, with the pitch diameter not more than 5.10 mm, and the major thread diameter not more than 4.53 mm; or,

has a 8 mm coarse thread size having 1.25 mm thread pitch, with the pitch diameter not more than 6.86 mm, and the major thread diameter not more than 6.13 mm; or,

has a 10 mm coarse thread size having 1.5 mm thread pitch, with the pitch diameter not more than 8.62 mm, and the major thread diameter not more than 7.73 mm; or,

has a 12mm coarse thread size having 1.75 mm thread pitch, with the pitch diameter not more than 10.37 mm, and the major thread diameter not more than 9.32 mm; or,

has a 14mm coarse thread size having 2.00 mm thread pitch, with the pitch diameter not more than 12.12 mm, and the major thread diameter not more than 10.92 mm; or,

has a 16 mm coarse thread size having 2.00 mm thread pitch, with the pitch diameter not more than 14.03 mm, and the major thread diameter not more than 12.77 mm.
A member, a nut or a bolt according to any one of the preceding claims, wherein the screw thread has an asymmetric flank configuration.
A member, a nut or a bolt according to claim 14, wherein a non-load bearing flank of the screw thread is reduced in size relative to an opposite load bearing flank thereof.
A member, a nut or a bolt according to any one of the preceding claims, wherein when the screw thread is female it has a minor diameter not less than 7.7% more than an industry standard basic minor diameter specified for the thread size and where the screw thread is male it has a major diameter not less than 7.7% less than an industry standard basic major diameter for the thread size.
A member or bolt, or a nut according to any one of the preceding claims, wherein the screw thread is female having a pitch diameter, and the minor diameter approximately the same as the pitch diameter, or wherein the screw thread is male having a pitch diameter, and the major diameter approximately the same as the pitch diameter.
A member, a bolt or a nut according to any one of the preceding claims, wherein the pitch diameter is an industry standard basic pitch diameter specified for a particular thread size.